A light-emitting device provided with a light-emitting element such as a light-emitting diode as a light source is utilized, for example, in a backlight of a liquid crystal display or the like. In the lighting device that is required to planarly irradiate light without unevenness in luminance, like a backlight, it is preferred if a light-emitting device that controls distribution characteristics by expanding the light emitted by the light-emitting element and emitting the light outward is utilized.
Examples of the light-emitting device described above are disclosed in Patent Documents 1 and 2. The structure of this light-emitting device will be described with reference to FIG. 14. FIG. 14 is a top view and cross-sectional view showing a schematic structure of a conventional light-emitting device. FIG. 14A is a top view, and FIG. 14B is a cross-sectional view showing an X-X cross section in FIG. 14A. Here, electrodes, wiring and the like are omitted in FIG. 14, for simplification of illustration.
As shown in FIG. 14, a light-emitting device 100 comprises a substrate 101 and a light-emitting element 102 provided on the surface of the substrate 101, and a resin body 103 that seals the light-emitting element. An opposite surface 103a that is opposed to a light-emitting surface (surface on the side opposite to the substrate 101) of the light-emitting element 102 in the resin body 103 is a depressed surface that is concavely depressed. Also, the depressed surface is an inclined surface of an inverted cone. Furthermore, the outer shape of the depressed surface of the resin body 103 is curved convex upward in the cross section that is perpendicular to the surface of the substrate and cut so as to pass through the center of the light-emitting surface of a light source (light-emitting element 102). In the light-emitting device 100, a part of the light emitted by the light-emitting element 102 is totally reflected on this depressed surface to return into the resin body 103, thereby expanding the light emitted by the light-emitting element 102 and emitting the light outward. As described above, since it is not necessary to separately provide a member that controls light distribution characteristics such as a lens, it is possible to reduce the number of the components of the light-emitting device 100.